The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
When the surface water is heated by the sun it dissolves more salt i believe
<span>The
absorption of iron is reduced when you have a diet high in fiber and
phytates. Even though an excess of fiber can have an effect in the
body’s ability to absorb some minerals, fiber is very safe and even
necessary in reasonable amounts. phytatic acids on the other hand are
responsible of binding metallic cations reducing the capacity of the
body of absorbing iron, calcium and zinc and should be consumed with
moderation.</span>
